Virtual Organ Computer-aided Analysis Technique Research Articles

Concordance between US and MRI Two-Dimensional Measurement and Volumetric Segmentation in Fetal Ventriculomegaly.

We provide a study comparison between two-dimensional measurement and volumetric (3D) segmentation of the lateral ventricles and brain structures in fetuses with isolated and non-isolated ventriculomegaly with 3D virtual organ computer-aided analysis (VOCAL) ultrasonography vs. magnetic resonance imaging (MRI) analyzed with 3D-Slicer software. In this cross-sectional study, 40 fetuses between 20 and 38 gestational weeks with various degrees of ventriculomegaly were included. A total of 71 ventricles were measured with ultrasound (US) and with MRI. A total of 64 sonographic ventricular volumes, 80 ventricular and 40 fetal brain MR volumes were segmented and analyzed using both imaging modalities by three observers. Sizes and volumes of the ventricles and brain parenchyma were independently analyzed by two radiologists, and interobserver correlation of the results with 3D fetal ultrasound data was performed. The semiautomated rotational multiplanar 3D VOCAL technique was performed for ultrasound volumetric measurements. Results were compared to manually extracted ventricular and total brain volumes in 3D-Slicer. Segmentation of fetal brain structures (cerebral and cerebellar hemispheres, brainstem, ventricles) performed independently by two radiologists showed high interobserver agreement. An excellent agreement between VOCAL and MRI volumetric and two-dimensional measurements was established, taking into account the intraclass correlation coefficients (ICC), and a Bland-Altman plot was established. US and MRI are valuable tools for performing fetal brain and ventricular volumetry for clinical prognosis and patient counseling. Our datasets could provide the backbone for further construction of quantitative normative trajectories of fetal intracranial structures and support earlier detection of abnormal brain development and ventriculomegaly, its timing and progression during gestation.

Reference Intervals of Fetal Cardiac Volume Between 14 and 40 Weeks of Gestation.

To construct the reference intervals for the cardiac volume (CV) of normal fetuses between 14 and 40 weeks of pregnancy. Low risk singleton pregnancies with normal fetuses were prospectively recruited to acquire 4D-cardio-spatiotemporal image correlation volume datasets (VDS). Subsequent off-line analyses of VDS were anonymously performed to calculate CV using the Virtual Organ Computer-aided AnaLysis technique. The reference intervals were established as a function of gestational age (GA), biparietal diameter (BPD), head circumference (HC), and estimated fetal weight (EFW) based on the best-fitted models for both mean and standard deviation (SD). A total of 668 VDS were successfully calculated for CV. The best-fitted models for the means and SDs are as follow: 1) GA in week=6.422 + e(-100.653 × GA) (SD=0.641 - (0.170 × GA) + (0.009 × GA2 )). 2) BPD=0.016 × (BPD)3.589 (SD=2.663 - (1.410 × BPD) + (0.224 × BPD2 )). 3) HC=0.00017 × (HC)3.537 (SD=2.341 - (0.341 × HC) + (0.015 × HC2 )). The CV progressively increased with advancing fetal age (GA) and size (BPD, HC). The reference intervals of CV, theoretically best representing cardiac size, in relation to GA, BPD, HC, and EFW were first established and Z-score was readily calculated. These will be helpful in detection of cardiac abnormalities, especially those associated with cardiomegaly.

Effectiveness of placental volume measured by virtual organ computer-aided analysis in prediction of fetal hemoglobin Bart's disease in late first trimester.

To evaluate the effectiveness of placental volume measured by virtual organ computer-aided analysis (VOCAL) at 12 to 14 weeks of gestation in predicting fetal hemoglobin (Hb) Bart's disease among pregnancies at risk. This study involves 3-dimensional ultrasound (3D-US) volume datasets derived from pregnancies at risk of fetal Hb Bart's disease at 12 to 14 weeks of pregnancy. VOCAL technique was used to measure and calculate placental volume by the authors, who did not know the fetal diagnosis. Placental thickness was also measured. The diagnostic values of placental volume and placental thickness in prediction of fetal Hb Bart's disease were calculated. Sixty-five volume datasets, including 22 datasets of the affected fetuses and 43 unaffected fetuses, were included. The mean placental volume (±SD) of the affected cases was significantly higher than that of the unaffected ones, 85.35 ± 20.84 cm3 vs 52.24 ± 19.01 cm3 (Student's t test, P < .001). In predicting Hb Bart's disease, placental volume and placental thickness had sensitivities of 77.3% and 72.7% respectively as well as specificities of 88.37% and 76.7% respectively. Of fetuses at risk of Hb Bart's disease, 3D-US VOCAL placental volume may be useful in early detection of affected fetuses. Its effectiveness is superior to that of conventional placental thickness measurement.

Application of 2- and 3-Dimensional Sonography Using the Virtual Organ Computer-Aided Analysis Technique to Measure the Hippocampal Formation and Its Correlation With Corrected Gestational Age in Neonates.

The purpose of this study was to use transcranial 2- and 3-dimensional sonography with the Virtual Organ computer-aided analysis (GE Healthcare, Milwaukee, WI) technique to observe the morphologic characteristics of the hippocampal formation and to analyze its correlation with the corrected gestational age. Transcranial sonography was performed from the sagittal plane of the anterior fontanel to the sagittal plane of the posterior horn of the lateral ventricle. The morphologic characteristics of the hippocampal formation in 183 singleton neonates with a corrected gestational age of 32 to 43 weeks were observed. The long diameter, short diameter, area, and perimeter of the hippocampal formation were all quantitatively measured. The volume of the hippocampal formation was measured by 3-dimensional sonography using the Virtual Organ computer-aided analysis technique. The correlation between the corrected gestational age and each parameter was analyzed. The display rate of the hippocampal formation was 100% in the neonates with a typical hippocampus shape. In healthy neonates with a corrected gestational age of 32 to 43 weeks, the long and short diameters, area, perimeter, and volume of the hippocampal formation were all positively correlated with the gestational age. Transcranial sonography could be used as a conventional approach for evaluation of the development of the hippocampal formation in neonates.

Three‐Dimensional Power Doppler Evaluation of Cerebral Vascular Blood Flow: A Novel Tool in the Assessment of Fetal Growth Restriction

To determine whether fetuses with fetal growth restriction (FGR) are more likely to have abnormal cerebral vascular flow patterns compared to fetuses who are appropriate for gestational age (AGA) when quantified by using 3-dimensional (3D) power Doppler ultrasound. We conducted a prospective cohort study of singleton gestations presenting for growth ultrasound examination between 24 and 36 weeks' gestation. Patients with FGR (estimated fetal weight < 10th percentile) were enrolled and matched 1:1 for gestational age (±7 days) with AGA fetuses. A standardized 3D power Doppler image of the middle cerebral artery territory was obtained from each patient. The vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) were calculated by the Virtual Organ computer-aided analysis technique (GE Healthcare, Milwaukee, WI). These indices were compared between FGR and AGA fetuses and correlated with 2-dimensional Doppler parameters. Neonatal outcomes were also compared with respect to the 3D parameters. Of 306 patients, there were 151 cases of FGR. There was no difference in the VI (6.0 versus 5.7; P = .65) or VFI (2.0 versus 1.8; P = .31) between the groups; however, the FI was significantly higher in FGR fetuses compared to AGA controls (33.9 versus 32.3; P = .009). There was a weak, but significant, negative correlation between the FI and both the middle cerebral artery pulsatility index (r = -0.34; P < .001) and cerebroplacental ratio (r = -0.29; P < .001). Within the FGR group, there was no difference in any of the 3D vascular indices with regard to neonatal outcomes. Three-dimensional power Doppler measurement of cerebral blood flow, but not the vascularization pattern, is significantly altered in FGR. This measurement may play a future role in distinguishing pathologic FGR from constitutionally small growth.

Reference ranges of placental volume measured by virtual organ computer-aided analysis between 10 and 14 weeks of gestation.

To establish the reference ranges of the placental volume between 10 and 14 weeks of gestation of Thai fetuses. The placental volumes were acquired in normal pregnancies between 10 and 14 weeks of gestation using transabdominal three-dimensional ultrasound. The placental volume was then analyzed using VOCAL (virtual organ computer-aided analysis) technique with a rotation angle of 30°. The measured values were regressed to identify the best-fit model. A total of 236 volume datasets met the inclusion criteria and were used for offline analysis. Placental volume significantly increased with increasing crown-rump length (CRL). The best-fit regression models for predicted mean and SD as a function of CRL, available for z score calculation and construction of the percentile chart, are as follows: [Formula: see text] CONCLUSION: Reference ranges of placental volume have been constructed. This normative data may be a useful tool in the evaluation of various conditions affecting placental size, eg, fetal hemoglobin Bart's disease. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:185-191, 2017.

Assessing the accuracy and reliability of ultrasonographic three-dimensional parathyroid volume measurement in a patient with secondary hyperparathyroidism: a comparison with the two-dimensional conventional method.

PurposeThe purpose of this study was to investigate the accuracy and reliability of the semi-automated ultrasonographic volume measurement tool, virtual organ computer-aided analysis (VOCAL), for measuring the volume of parathyroid glands.MethodsVolume measurements for 40 parathyroid glands were performed in patients with secondary hyperparathyroidism caused by chronic renal failure. The volume of the parathyroid glands was measured twice by experienced radiologists by two-dimensional (2D) and three-dimensional (3D) methods using conventional sonograms and the VOCAL with 30°angle increments before parathyroidectomy. The specimen volume was also measured postoperatively. Intraclass correlation coefficients (ICCs) and the absolute percentage error were used for estimating the reproducibility and accuracy of the two different methods.ResultsThe ICC value between two measurements of the 2D method and the 3D method was 0.956 and 0.999, respectively. The mean absolute percentage error of the 2D method and the 3D VOCAL technique was 29.56% and 5.78%, respectively. For accuracy and reliability, the plots of the 3D method showed a more compact distribution than those of the 2D method on the Bland-Altman graph.ConclusionThe rotational VOCAL method for measuring the parathyroid gland is more accurate and reliable than the conventional 2D measurement. This VOCAL method could be used as a more reliable follow-up imaging modality in a patient with hyperparathyroidism.

Three-dimensional ultrasound using the VOCAL technique for estimation of reference values of fetal thigh volume in normally grown Egyptian fetuses from 20 to 41 weeks

Objective: To establish the normal reference values for the fetal thigh volume (FTV) of normally grown Egyptian fetuses using three-dimensional (3D) virtual organ computer aided analysis (VOCAL) method.Patients and methods: A total of 334 Egyptian pregnant women carrying a singleton living normally grown fetus between the 20th and the 41st weeks of gestation were enrolled in this cross-sectional study. FTV was measured using the 3D VOCAL method with 30° rotation. Estimated fetal weight (EFW) was calculated based on Hadlock formula.Results: FTV correlated strongly with gestational age (r = 0.921, p < 0.001) and EFW (r = 0.891, p < 0.001). For clinical application, a nomogram of growth percentiles of FTV was produced.Conclusion: Reference values of FTV between 20th and 41st weeks of gestation in normally grown Egyptian fetuses were provided using the 3D VOCAL method. These data may be helpful to assess fetal growth and to diagnose deviation from normal.

First trimester pregnancy volumes and subsequent small for gestational age fetuses

To examine whether in the first trimester, placental, gestational sac and fetal volumes are different in pregnancies that result in small for gestational age (SGA) compared to average for gestational age (AGA) neonates. Case-control study comparing first trimester 3D volumes of the placenta, the fetus and the gestational sac between SGA and AGA pregnancies. 3D volumes were acquired for quality assurance and documentation. Pregnancy volumes were calculated by the virtual organ computer-aided analysis technique. Linear regression analysis was used to compute a normal range for the placental, gestational sac and fetal volume based on the crown rump length (CRL) in AGA pregnancies. Multiple regression analysis was used to examine significant influencing covariates. A Student's t test was used to compare the difference between the SGA and AGA group. The study population consisted of 19 first trimester pregnancies with subsequent SGA neonates and 105 control pregnancies. In the AGA group, all pregnancy volumes were significantly dependent on the CRL. After controlling the CRL effect, the placental, gestational sac and fetal volumes were not significantly different between the SGA and AGA group. First trimester 3D pregnancy volume measurements are not different in SGA or AGA pregnancies.

Renal Volumes Measured by 3-Dimensional Sonography in Healthy Fetuses From 20 to 40 Weeks

The purpose of this study was to establish reference values for fetal kidney volumes as a function of gestational age, estimated by 3-dimensional sonography using the Virtual Organ Computer-Aided Analysis (VOCAL) technique (GE Healthcare, Kretztechnik, Zipf, Austria). Volumes of right and left kidneys were assessed in 213 healthy fetuses by 3-dimensional sonography using the VOCAL technique. Inclusion criteria were healthy women with singleton pregnancies, unremarkable comprehensive fetal sonographic findings, well-known gestational age established by first-trimester sonography, and gestational ages between 20 and 40 weeks. Exclusion criteria were patients lost to follow-up and birth weight abnormalities. Each patient was scanned once during pregnancy. Regression analysis was used to calculate unified formulas. The mathematical models calculated in the study were as follows: expected right kidney volume = exp[-1.01 + (0.12 × gestational age)]; and expected left kidney volume = exp[-0.90 + (0.12 × gestational age)]. No significant intraobserver or inter-observer variability was observed for the determined volumes. Reference values for right and left fetal kidney volumes throughout gestation using the rotational technique (VOCAL) are described. The use of this technique might aid in further definition of gestational age kidney volume standards to help in defining variations from the norm.

The effect of fetal congenital heart disease on in utero urine production rate

To evaluate the influence of congenital heart disease (CHD) or congestive heart failure (CHF) on fetal urine production rate (UPR) and to establish normal reference intervals. A cross-sectional study was performed on normal fetuses (n = 314) and on fetuses with CHD (n = 49). CHD cases were divided into groups on the basis of heart function as defined by Huhta score: with CHF (n = 11) and without CHF (n = 38). Fetal bladder volume was measured by two-dimensional as well as three-dimensional ultrasound with the Virtual Organ Computer-aided Analysis technique. In normal fetuses, UPR increased with gestational age from a mean value of 4.5 mL/h at 21 weeks to 66.5 mL/h at 40 weeks. There were no significant differences in UPR between CHD cases without CHF and controls (P = 0.581). However, fetuses with CHF had decreased UPR values (Controls vs. CHF, P = 0.007) compared with the controls. The interobserver and intraobserver variability for assessment of UPR was better using three-dimensional rather than two-dimensional US. Fetal UPR can be reproducibly measured by the Virtual Organ Computer-aided Analysis technique. It appears that heart function, rather than CHD, affects fetal UPR. Fetal UPR may therefore be an additional indicator of CHF.

Comparison of inter‐ and intraobserver agreement and reliability between three different types of placental volume measurement technique (XI VOCAL™, VOCAL™ and multiplanar) and validity in the in‐vitro setting

To compare XI VOCAL (eXtended Imaging Virtual Organ Computer-aided AnaLysis) for three-dimensional (3D) ultrasound volumetry of the placenta and of phantom objects with a rotational method using VOCAL and with the multiplanar method. We acquired 3D volume datasets from 32 fetuses at 11-14 weeks' gestation. Placental volume was calculated twice by each of two observers using XI VOCAL (with 5, 10, 15 and 20 slices), multiplanar (1-mm interval) and VOCAL (with 12 degrees, 18 degrees and 30 degrees rotation) methods. In addition, validity was assessed using the in-vitro setting with three phantom objects of known volume. Both inter- and intraobserver reliabilities were very high for all three methods. There was no systematic bias between any two methods except between XI VOCAL (10 slices) and the multiplanar (1-mm interval) method, with a smaller volume using the former method. The limits of agreement were wide between any two of the three methods. In the in-vitro setting, there was a trend towards less valid measurements with the XI VOCAL technique and fewer slices. With the same number of steps, measurements made with VOCAL (12 degrees and 18 degrees) were more valid than were those made with XI VOCAL (15 and 10 slices, respectively). XI VOCAL cannot be used interchangeably with VOCAL or multiplanar techniques in measuring placental volume at 11-14 weeks' gestation.

Assessment of cyst content using mean gray value for discriminating endometrioma from other unilocular cysts in premenopausal women

To assess whether the analysis of cyst content using mean gray value (MGV) can discriminate ovarian endometriomas from other unilocular ovarian cysts in premenopausal women. Stored three-dimensional (3D) volumes from 54 unilocular ovarian cysts diagnosed in 50 premenopausal women (mean age, 37 (range, 22-50) years) were analyzed to calculate the MGV from cyst content. Cysts with solid components or septations were excluded. MGV was calculated in all cases with the Virtual Organ Computer-aided AnaLysis technique. The B-mode presumptive diagnosis based on the examiner's subjective impression was also recorded. Sixteen of the cysts resolved spontaneously and were given a final clinical diagnosis of hemorrhagic functional cyst, while 38 cysts were removed surgically (diagnosed histologically as seven simple cysts, three hemorrhagic cysts, 20 endometriomas, five mucinous cysts and three paraovarian cysts). B-mode diagnoses were as follows: seven simple cysts, 18 hemorrhagic cysts, 24 endometriomas, three mucinous cysts and two paraovarian cysts. MGV was significantly higher in ovarian endometrioma when compared with all other kinds of cyst. The receiver-operating characteristics curve showed that using an MGV cut-off >or= 15.560 had a sensitivity of 85% and a specificity of 76.5% for diagnosing ovarian endometrioma (area under the curve, 0.831; 95% CI, 0.718-0.944). These figures were similar to those for B-mode diagnosis (sensitivity, 90%; specificity, 82%) (McNemar test, P = 1.000). Combining B-mode and MGV gave a sensitivity of 80% and a specificity of 91%. Cyst content MGV is higher in ovarian endometrioma than it is in other unilocular ovarian cysts. The diagnostic performance of MGV is similar to that of the examiner's subjective impression. The combination of both criteria achieves the highest specificity.

Quantitative and morphological assessment of early gestational sacs using three‐dimensional ultrasonography

Our main objective was to determine the value of three-dimensional ultrasonography (3DUS) and Virtual Organ Computer-aided AnaLysis (VOCAL) in the evaluation of gestational sac volume and morphology during early pregnancy. Twenty-eight normal early pregnancies were scanned approximately every 2 weeks using transabdominal (TAS) and transvaginal (TVS) sonography. The VOCAL technique was used to create computerized surface models to classify gestational sac shapes as discoid or ellipsoid. Serial sac volume changes were analyzed using repeated measures ANOVA. Bland-Altman plots determined examiner bias and limits of agreement (LOA) for sac volume measurements. Gestational sac volumes were compared between the two-dimensional (2D) ellipsoid and VOCAL techniques. Differences between volume measurements were tested using the two-tailed paired t-test with statistical significance at the P < 0.05 level. Each subject was examined at a mean +/- SD menstrual age of 7.9 +/- 0.6 weeks (Scan 1), 9.9 +/- 0.6 weeks (Scan 2), and 11.9 +/- 0.6 weeks (Scan 3). Sac volumes significantly increased over time from 22 +/- 11 mL at Scan 1, to 57 +/- 21 mL at Scan 2 and 116 +/- 35 mL at Scan 3 (P < 0.001). Predominant sac shapes were classified as ellipsoid (76.2%) or discoid (23.8%). Additional descriptors included: concave (60.7%), irregular (53.6%), or smooth (7.1%), with 19% of the overall group having more than one additional shape attribute. Clinically acceptable volume measurement bias and agreement were found for the following comparisons: (1) TAS versus TVS; (2) interobserver volume measurements; and (3) intraobserver volume measurements. The VOCAL technique yielded slightly greater sac volumes (64 +/- 45.4 mL) when compared to the 2D ellipsoid model (48.6 +/- 36.8 mL) (28.9 +/- 24.3% (95% limit of agreement range, - 18.7 to 76.5%), P < 0.001). Reproducible sac volume measurements can be obtained using VOCAL with either TAS or TVS. Early gestational sacs variably appear as discoid or ellipsoid structures with a concave indentation from the placenta. Sac volumes can be underestimated if an ellipsoid shape is assumed. Morphological and quantitative analysis of the gestational sac may provide baseline parameters for studying patients at risk for early pregnancy failure.

Evaluation of the Agreement Between 3-Dimensional Ultrasonography and Magnetic Resonance Imaging for Fetal Lung Volume Measurement

The purpose of this study was to assess the agreement between 3-dimensional ultrasonography (3DUS) and magnetic resonance imaging (MRI) for lung volumetry in fetuses with and without abnormalities associated with lung hypoplasia. Fifty-nine singleton pregnancies were evaluated. Cases were separated into groups 1 and 2, according to the presence or absence of malformations associated with lung hypoplasia, respectively. Fetal lung volume was calculated by the Virtual Organ Computer-Aided Analysis (VOCAL) program of the 3DUS and the MRI. In both groups, measurements performed with all VOCAL angles were compared among themselves and with those obtained by MRI. Bland-Altman tests and analysis of variance were used for this purpose. In groups 1 and 2, the mean lung volume obtained with each rotation angle of the VOCAL technique was significantly smaller than the mean volume calculated by MRI (P < .001), and the mean volume obtained with the 30 degrees rotation step was significantly smaller than those obtained with the other rotation steps of the VOCAL technique. Bland-Altman tests confirmed this underestimation and showed a broad 95% confidence interval when the VOCAL angles were compared with those of MRI and when the 30 degrees rotation step was compared with the other VOCAL steps. There was a substantial discrepancy between 3DUS and MRI and between the 30 degrees rotation step of the VOCAL technique and the other rotation angles, for lung volume measurement in fetuses with and without abnormalities associated with lung hypoplasia.

Lung and heart volumes by three-dimensional ultrasound in normal fetuses at 12–32 weeks' gestation

To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.